Calutrons of the multiple ion beam type



y 0 9 6 c. LAWRENCE 2,754,423

CALUTRONS OF THE MULTIPLE ION BEAM TYPE Filed July 27, 1944 I5 Sheets-Sheet 1 ar -1. HEA TER A Rc A6651. ERA TING F/LAMENT SUPPL Y SUPPL IE5 ELECTRODE SUPPLIES SUPPLIES 37 32 6 5133.5 .514 4 3 4i [Q /4 W A W/ WWW AA \l/ g A A A AA a HM l- -/3 AA A A A [L [L AA 24 22 /T (T H 18 43 MA I I I I (1A A A 1M 28 35 2.9 38 23 30 4/ (MAGNET/C F/ELD l5 INVENTOR.

Z ERNEST 0. LAWRENCE /2 AZ A M ATTORNEY.

July 10, 1956 E. o. LAWRENCE 2,754,423

CALUTRONS OF THE MULTIPLE ION BEAM TYPE Filed July 27, 1944 3 Sheets-Sheet 2 INVENTOR. ERNEST 0. LAWRENCE w a, M

ATTORNEY.

July 10, 1956 E. o. LAWRENCE CALUTRONS OF THE MULTIPLE ION BEAM TYPE Filed July 27, 1944 3 Sheets-Sheet 3 Wm M Mm Nh INVENTOR. ERNEST 0. ZAWRENCE ATTORNEY.

llnited States harem G l CALUTRONS F TIE MULTIPLE ION BEAM TYPE Ernest 0. Lawrence, Berkeley, Calif., assignor to the United States of America as represented by the United States Atomic Energy Commission Application July 27, 1944, Serial No. 546,919

Claims. (C1. 25041.9)

The present invention relates to calutrons and more particularly to improvements in calutrons of the multiple ion beam type disclosed in the copending application of Ernest 0. Lawrence, Serial No. 536,401, filed May 19, 1944, now Pat. No. 2,714,664.

At the outset, it is noted that a calutron is a machine of the character of that disclosed in the copending application of Ernest 0. Lawrence, Serial No. 557,784, filed October 9, 1944, now Pat. No. 2,709,222, and is employed to separate the constituent isotopes of an element and, more particularly, to increase the proportion of a selected isotope in an element containing several isotopes in order to produce the element enriched with the selected isotope. For example, the machine is useful for separating the isotopes Li6 and Li7 and is especially useful in producing uranium enriched with U as pointed out in the above-mentioned copending application S. N. 557,784.

Such a calutron essentially comprises means for vaporizing a quantity of material containing an element that is to be enriched with a selected one of its several isotopes; means for subjecting the vapor to ionization, whereby at least a portion of the vapor is ionized causing ions of the several isotopes of the element to be produced; electrical means for segregating the ions from the un-ionized vapor and for accelerating the segregated ions to relatively high velocities; electromagnetic means for deflecting the ions along curved paths, the radii of curvature of the paths of the ions being proportional to the square roots of the masses of the ions, whereby the ions are concentrated in accordance with their masses; and means for de-ionizing and collecting the ions of the selected isotope thus concentrated, thereby to produce a deposit of the element enriched with the selected isotope, all as set forth in the Lawrence application, Serial No. 557,784.

A calutron of the multiple ion beam type disclosed in the Lawrence application, Serial No. 536,401, new Pat. No. 2,714,664, essentially comprises an evacuated tank, a plurality of devices arranged in the tank and adapted to ionize material containing isotopes of an element that is to be enriched with respect to one of its isotopes, a plurality of transmitters arranged to transmit a corresponding plurality of ion beams from the devices, and one or more receivers in which the element to be enriched with respect to the selected isotope is deposited. In one form of this calutron there is provided a plurality 'of independent ion transmitter units arranged to transmit a corresponding plurality of ion beams to a single receiver; and in a modified form of this calutron there is provided a single transmitter unit comprising a plurality of individual ion beam transmitters arranged to transmit a corresponding plurality of ion beams to a corresponding plurality of receivers.

While these forms of calutron of the multiple ion beam type are entirely satisfactory in operation, they do not efiect the economy of materials and the conservation of space desirable in plant applications.

Accordingly, it is an object of the invention to provide 2,754,423 Patented July 10, 1956 ice 2 in a calutron a single transmitter unit comprising a plurality of individual transmitters arranged to transmit a corresponding plurality of ion beams to a single receiver.

Another object of the invention is to provide an improved ion transmitter unit arranged to transmit a plurality of ion beams traversing paths of different curvatures.

A further object of the invention is to provide an ion transmitter unit comprising a plurality of mutually insulated gas ionizing devices supplied with gas to be ionized from a single chamber and arranged to transmit a plurality of ion beams traversing paths of dilierent curvatures.

A calutron embodying the features of the present invention comprises a transmitter unit including a plurality of individual ion beam transmitters, a receiver, and means for focusing the ion beams onto the receiver. Also, this ion transmitter unit comprises a plurality of mutually insulated gas ionizing devices, a chamber containing a gas to be ionized, and means for supplying the gas from the chamber to the gas ionizing devices.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which:

Figure l is a diagrammatic plan view of a calutron incorporating the present invention;

Fig. 2 is a diagrammatic sectional view of the calutron taken along the line 2-2 in Fig. 1;

Fig. 3 is a transverse sectional view of an ion transmitter unit incorporated in the calutron, taken along the line 3-3 in Fig. 4;

Fig. 4 is a longitudinal sectional view of the ion transmitter unit taken along the line 44 in Fig. 3; and

Fig. 5 is a front elevational view of the ion transmitter unit shown in Figs. 3 and 4.

Figs. 4 and 5 are drawn to a reduced scale compared to Fig. 3.

Referring now more particularly to Figs. 1 and 2 of the drawings, there is illustrated a plural beam calutron 10 incorporating the present invention. This calutron comprises a magnetic field structure including upper and lower pole pieces 11 and 12, provided with substantially parallel spaced-apart pole faces, and a tank 13 disposed between the pole faces. The pole pieces 11 and 12 carry windings, not shown, which are adapted to be energized in order to produce a substantially uniform and relatively strong magnetic field therebetween, which magnetic field passes through the tank 13 and the various parts housed therein. The tank 13 is of tubular configuration, being substantially U- or crescent-shaped in plan, and comprising substantially fiat parallel spaced-apart top and bottom walls 14 and 15, upstanding curved inner and outer side walls 16 and 17, and end walls 18 and 19. The end walls 18 and 19 close the opposite ends of the tubular tank 13 and are adapted to be removably secured in place, whereby the tank 13 is hermetically sealed. Also, vacuum pumping apparatus 13a is associated with the tank 13, whereby the interior of the tank 13 may be evacuated to a low pressure of the order of 10* to 10* mm. Hg. Preferably, the component parts of the tank 13 are formed of steel, the top and bottom walls 14 and 15 thereof being spaced a short distance from the pole faces of the upper and lower pole pieces 11 and 12, respectively, the tank 13 being retained in such position in any suitable manner, whereby the top and bottom walls 14 and 15 constitute in effect pole pieces with respect to the interior of the tank 13.

The removable end wall 18 suitably supports an ion transmitter unit 20 comprising a charge receptacle 21 and a plurality of mutually insulated arc-blocks 22, 23,

' :P and 24-, communicating therewith through corresponding passages 25, 26 and 27 on the rear walls thereof. The arc-blocks 22, 23, and 24 are formed, at least partially, of brass or the like and are substantially rectangularshaped in plan. Upstanding slots 28, 29, and 39 are formed in the forward walls of the respective arc-blocks 22, 23, and 2 3, remote from the corresponding passages 25, 26, and 27 communicating with the charge receptacle 21. Thus, each arc-block is of hollow construction, the cavity therein communicating with the interior of the charge receptacle 21. V 7

An electric heater 31 is arranged in heat exchange rela tion with the charge receptacle 21 and is adapted to be connected to a suitable source of heater supply, whereby the charge receptacle 21 may be appropriately heated, the charge receptacle 21 being formed of steel or the like.

Also, the removable end wall 18 carries a plurality of: filamentary cathodes 32, 33, and 34, adapted to be connected to suitable associated and independent sources of filament supply, each filamentary cathode 32, 33, and 34 respectively overhanging the upper ends of the arcblocks 22, 23, and 24 and arranged in alignment with respect to the upper end of'the cavity formed in the corresponding arc-block.

The left arc-block 22 carries an anode 35 disposed adjacent the lower end thereof and arranged in alignment with respect to the cavity formed therein. Also, the arc-block 22 carries a collimating electrode 36 disposed adjacent the upper end thereof and having an elongated collimating slot 37 formed therethrough and arranged in alignment with respect to the filamentary cathode 32, as well as the anode 35 and the cavity formed in the arc-block 22. Both the anode 35 and the collimating electrode 36 are electrically connected to the arcblock 22, which in turn is connected to the positive terminal of a suitable first source of accelerating electrode supply, as explained more fully hereinafter. Also, the filamentary cathode 32 and the cooperating anode 35 are adapted to be connected to a suitable first source of arc supply.

The middle arc-block 23 carries an anode 38 disposed adjacentthe lower end thereof and arranged in alignment with respect to the cavity formed therein. Also, the arc-block 23 carries a collimating electrode 33 disposed adjacent the upper end thereof and having an elongated collimating slot 49 formed therethrough and arranged in alignment with respect to the filamentary cathode 33, as well as the anode38 and the cavity formed in the arc-block 23. Both the anode 38 and the collimating electrode 39 are electrically connected to the arc-block 23, which in turn is connected to the positive terminal of a second suitable source of accelerating electrode supply, as explained more fully hereinafter. Also, the filamentary cathode 33 andthe cooperating anode 38 are adapted to be connected to a second suitable source of arc supply.

The right arc-block 24 carries an anode 41 disposed adjacent the lower end thereof and arranged in alignment with respect to the cavity formed therein. Also, the arc-block 24 carries a collimating electrode 42 disposed adjacent the upper end thereof and having an elongated collimating slot 43 formed therethrough and arranged in alignment with respect to the filamentary cathode 34, as well as the anode 41 and the cavity formed in the arc-block 24. Both the anode 41 and the collimating electrode 42 are electrically connected to the arc-block 24, which in turn is connected to the positive terminal of a third suitable source of accelerating electrode supply, as explained more fully hereinafter. Also, the filamentary cathode 34 and the cooperating anode 41 are adaptedto be connected to a third suitable source of arc supply.

Further, the removable end wall 18 carries ion accelerating structure 44, constituting a component, part of the transmitter unit 2% and formed at least partially of tungsten or the like, and disposed in spaced-apart relation with respect to the walls of the arc-blocks 22, 23, and 24 in which the slots 23, 29, and 30 are formed. More specifically, slits 145, 1%, and 147 are formed in the ion accelerating structure and arranged in substantial alignment with respect to the respective slots 28, 29, and 39 formed in the walls or" the arc-blocks 22, 23, and 24. It is to be noted that the three arcblocks 22, 23, and 24 are disposed along a line transverse to the magnetic field and that the slots 23, 29, and 35? in the respective arc-blocks 22, 23, and 24 lie in a first plane parallel to the magnetic field and said line, and that the slits 145, 145, and 147 in the accelerating structure 44 lie in a second plane parallel to and spaced from said first plane. The three sources of accelerating electrode supply are adapted to be connected between the arc blocks 22, 23, and 24 and the ion accelerating structure 44, the positive terminals of the supplies mentioned being respectively connected to the arcblocks 22, 23, and 24, and the negative terminals to the ion accelerating structure 44. The negative terminals of the ion accelerating electrode supplies are grounded. Further, the tank Walls are grounded.

The removable end wall 19 suitably supports an ion collector block or receiver unit 45, formed of stainless steel or the like, and provided with two laterally spacedapart cavities or pockets 46 and 47 which respectively communicate with slots &8 and 4-9 -formed in the wall of the collector block 45 disposed remote from the removable end wall 19, the slots 5-3 and 49 being aligned with the magnetic field and disposed in a plane substantially parallel to the plane of the slots 28, 2?, one and the plane of the slits 145, 146, and 147. It is noted that the pockets 46 and 47 are adapted to receive two constituent isotopes of an element which have been separated in the calutron 10, as explained more fully hereinafter. Finally, the collector block is electrically grounded.

Considering now the general principle of operation of the calutron 16, a charge comprising a compound of the element to be treated is placed in the charge receptacle 21, the compound of the element mentioned being one which may be readily vaporized. The end walls 18 and 19 are securely attached to the open ends of the tank 13, whereby the tank 13 is hermetically sealed. The operation of the vacuum pumping apparatus 13a associated with the tank 13 is then initiated. When a pressure of the order of lO to 10 mm. Hg is established within the tank, the electric circuits for the windings, not shown, associated with the pole pieces 11 and 12 are closed and adjusted, whereby a predetermined magnetic field is established therebetween traversing the tank 13. The electric circuit for the heater 31 is closed, whereby the charge in the charge receptacle 21 is heated and vaporized. The vapor fills the charge receptacle 21 and is conducted into the communicating cavities formed in the respective arc-blocks 22, 23, and 24 through the corresponding passages 25, 26, and 27. The electric circuits for the filamentary cathodes 32, 33, and 34 are closed, whereby the'filamentary cathodes are heated and rendered electron emissive. Then the electric circuits between the filamentary cathodes 32, 33, and 34 and the corresponding associated anodes 35, 38, and 41. are closed, whereby a plurality of arc dischargesis struck between the corresponding cathodes and anodes, electrons proceeding from the filamentary cathodes 32, 33, and 34 through the corresponding collimating slots 37, 4:), and 43 formed in the respective collimating electrodes 36, 39, and 42, to'the corresponding anodes 35, 38, and 41. The collimating slots 37, 4t and 43 formed in the collimating electrodes 36, 39, and 42 define the cross sections of the streams of electrons proceeding into the respective arc-blocks 22, 23, and 24, whereby each arc discharge has a ribbon-like configuration and breaks up the molecular form of the compound. to a considerable V extent, producing in" the cavities within the respective arc-blocks 22', 23, and 24 positive ions of the element that is to be enriched with the selected one of its isotopes. Each of the arc discharges so produced in the cavities of the arc-blocks 22, 23, and 24 is characterized by a high current, a low voltage, and a luminous plasma.

The electric circuits between the arc-blocks 22, 23, and 24 and the ion accelerating structure 44 are completed, the ion accelerating structure 44 being at a high negative potential with respect to the arc-blocks 22, 23, and 24, whereby the positive ions formed in the cavities within the arc-blocks 22, 23, and 24 are attracted toward the ion accelerating structure 44 and accelerated through the respective voltages impressed between the ion accelerating structure 44 and the arc-blocks 22, 23, and 24. More particularly, the positive ions proceed from the cavities formed in the arc-blocks 22, 23, and 24 through the respective slots 28, 29, and 30 formed in the walls thereof, and across the space between the ion accelerating structure 44 and the adjacent walls of the arc-blocks 22, 23, and 24, and thence through the corresponding slits 145, 146, and 147 formed in the ion accelerating structure 44 opposite the respective slots 28, 29, and 30. The high-velocity positive ions transmitted from the cavities of the respective arc-blocks 22, 23, and 24 form three vertical upstanding ribbons or beams proceeding through the slots 28, 29, and 30 in the arc-blocks 22, 23, and 24 and the respective aligned slits 145, 146, and 147 in the ion accelerating structure 44 in the same direction substantially normal to the planes of said slits and said slots.

As previously noted, the collector block 45, as well as the tank 13, is electrically connected to the ion accelerating structure 44, whereby there is an electric-fieldfree path for the high-velocity positive ions disposed be tween the ion accelerating structure 44 and the collector block 45 within the tank 13. The high-velocity positive ions are deflected from their normal straight-line paths and from the three vertical planes passing through the slots 28, 29, and 30 and the respective aligned slits 145, 146, and 147, due to the effect of the relatively strong magnetic field maintained through the space within the tank 13 through which the positive ions travel.

In the present arrangement the three transmitters, including the arc-blocks 22, 23, and 24 and the receiver 45, are arranged in a linear array. Each of the three ions beams is arcuate-shaped but substantially semicircular, the ions traveling in a clockwise direction, due to the disposition of the magnetic field; and the electric voltage produced by each of the three accelerating electrode supplies between the ion accelerating structure 44 and the corresponding arc-blocks 22, 23, and 24 is of such a value that high velocity ions are transmitted through the evacuated tank space from the corresponding transmitters to the single receiver 45. Also, each of the three ion beams is disposed substantially transversely of the longitudinal axis of the magnetic field.

It will be understood that the projection of the three ion beams with different radii, such that they are focused upon the single collector block 45, is accomplished by impressing the three different and appropriate accelerating electrode supply voltages between the ion accelerating structure 44 and the respective arc-blocks 22, 23, and 24 of the three ion beam transmitters. Of course, the accelerating electrode supply voltage impressed between the ion accelerating structure 44 and the left arc-block 22 is greater than, and the accelerating electrode supply voltage impressed between the accelerating structure and the right arc-block 24 is less than, that impressed between the ion accelerating structure 44 and the middle arc-block 23 in order to obtain the end explained, due to the fact that the radius of curvature of each of the ion beams is determined by the following formula:

In this formula, r is the radius of curvature of anion path, H is the magnetic field strength through which the ion travels, V is the accelerating voltage applied to the ion, in is the mass of the ion, and e is the charge of the ion; all taken in proper absolute units.

Due to differences in the masses of the isotopes of an element, such as uranium, ions of a relatively light isotope of the element in the beam transmitted from each of the blocks 22, 23, and 24, describe an interior arc of relatively short radius and are focused through the slot 43 into the pocket 46 formed in the collector block 45; Whereas ions of a relatively heavy isotope of the element in the beam transmitted from each of the blocks 22, 23, and 24, describe an exterior arc of relatively long radius and are focused through the slot 49 into the pocket 47 formed in the collector block 45. Accordingly, the relatively light ions are collected in the pocket 46 and are ClB-iOnlZCd to produce a deposit of the relatively light isotope of the element therein; while the relatively heavy ions are collected in the pocket 47 and are deionized to produce a deposit of the relatively heavy isotope of the element therein.

After all of the charge in the charge receptacle 21 has been vaporized, all of the electric circuits are interrupted and the end wall 18 is removed so that another charge may be placed in the charge receptacle 21 and subsequently vaporized in the manner explained above. After a suitable number of charges have been vaporized in order to obtain appropriate deposits of the isotope of the element in the pockets 46 and 47 of the collector block 45, the end wall 19 is removed and the deposits of the collected isotopes in the pockets 46 and 47 in the collector block 45 arereclaimed.

Of course, it will be understood that the various dimensions of the parts of the calutron it the various electrical potentials applied between the various electrical parts thereof, as well as the strength of the magnetic field between the pole pieces 11 and 12, are suitably correlated with respect to each other, depending upon the mass numbers of the several isotopes of the element which is to be treated therein. In this connection reference is again made to the copending application of Ernest 0. Lawrence, Serial No. 557,784, for a complete specification of a calutron especially designed for the production of uranium enriched with the isotope U By way of illustration, it is noted that when the calutron 10 is employed in order to produce uranium enriched with U the compound of uranium which is suggested as a suitable charge in the charge receptacle 21 is UCl4, as this compound may be readily vaporized and the molecular form of the vapor may be readily broken up to form positive ions of uranium with great facility. In this case, uranium enriched with U is collected in the pocket 46 of the collector block 45, and uranium comprising principally U is collected in the pocket 47 of the collector block 45. Also, it is noted that from a practical standpoint, the deposit of uranium collected in the pocket 46 of the collector block 45 contains considerable amounts of U in view of the fact that this isotope comprises the dominant constituent of normal uranium. Furthermore, the deposit of uranium collected in the pocket 46 of the collector block 45 contains a considerably increased amount of U in view of the fact that it is not ordinarily feasible to separate U and U in the production of relatively large quantities of uranium enriched with U for commercial purposes. Accordingly, in this example the uranium deposited in the pocket 46 of the collector block 45 is considerably enriched, both with U and with U and considerably impoverished with respect to U as compared to natural or normal uranium.

Referring now more particularly to Figs. 3 to S, inelusive, there are illustrated the structural details of the ion transmitter unit 20 which is arranged in the magnetic field between the pole pieces of the calutron in the manner previously explained. The transmitter unit 20 comprises a charge receptacle 21 and three mutually insulated arcblocks 22, 23, and 24 secured together in abutting sideby-side relation. The charge receptacle 21 comprises wall structure including a removable cover defining an upstanding cavity 51 therein, that is adapted to receive a removable charge bottle 52 containing a charge 53 which is to be vaporized.

The three arc-blocks, together with four upstanding strips 55, 56, 57, and 53 of electrically insulating material, form a front wall member of the source unit, which wall member is securely attached between opposite side walls 59 and 6b of a supporting member; An intermediate wall member 61 is positioned between the charge receptacle 21 and the front wall member comprising the arc-blocks 22, 23, and 24. The insulating strip 55 is L-shaped in plan, one side fitting between the side wall 59 of the supporting member and one side of the left arc-block 22, the other side of the insulating strip 55 fitting between the intermediate wall member 61 and the rear side of the left arc-block 22. The insulating strip 56 is positioned between the adjacent sides of the left arc-block 22 and the the middle arc-block 23. The insulating strip 57 is positioned between the adjacent sides of the middle arc-block 213 and the right arc-block 24. The insulating strip 53 is L-shaped in plan, one side fitting between the wall 69 of the supporting member and one side of the right arc-block 24, the other side fitting between the intermediate wall member 61 and the rear side of the right areblock.

The front wall member comprising the three arc-blocks 22,23, and 24 and the four insulating strips 55, 56, 57, an 58 together with the intermediate wall member 61 define an upstanding vapor distributing chamber '62. The vapor distributing chamber 62 communicates on one side with the cavity 51 in the charge receptacle through a tubular member 63, supported by the wall structure of the charge receptacle 21 and the intermediate wall member 61, and on the other side with the three upstanding arc chambers 64, 65, and 66 in the respective arc-blocks 22, 23, and 24 through three corresponding series of passages 25, 26, and 27 in the rear walls of the respective arc-blocks 22, 23, and 24.

The wall structure of the charge receptacle 21 has two upstanding cavities 70 formed therein, in which two elements of an electric heater 71 are arranged. Preferably, each element of the electric heater 71 comprises a coil of resistance wire wound upon a supporting insulator, as indicated, whereby each element of the electric heater ,71 may be independently placed in and removed from the associated cavities 7%. Thus, the charge receptacle 21, and consequently the charge bottle 52, may be appropriately heated in order to vaporize the charge 53 contained in the charge bottle 52. Similarly, the intermediate wall member 63. has two upstanding cavities 72 formed therein, in which two electric heating elements 73 are arranged. Preferably, each of the electric heating elements 7:3 comprises a coil of resistance wire wound upon a supporting insulator, as indicated, whereby each of the electric heating elements 73 may be independently placed in and removed from the associated cavities 72. Thus, the transmitter unit 29 and more particularly the distributing chamber 62 therein and the arc-blocks 22, 23, and 2-4 may be heated in order to prevent condensation of the contained vapor, as explained more fully hereinafter.

More particularly, the wall structure of the charge receptacle 21, the intermediate wall member 61, the tubular member 63, and the arc-blocks 22, 23, and 24, are formed of copper or brass and the electrically insulating strips 55, 56, 57, and 58 are formed of a material such as quartz, which while it insulates electrically, still permits a relatively free flow of heat between the arc-blocks 22,

23, and 24 and'the intermediate wall member 61. Thus,

' the parts of the source unit including the arc-blocks 22,

23, and 24, the insulating strips 55, 56, 57, and 58, the intermediate wall member 61, the charge receptacle 21, the charge container '52, and the tubular member 63,

which are exposed to vapors produced by heating the charge 53, may be heated to prevent condensation of the vapor at any point between the charge 53 and the arc chambers 64, 65, and 66 in the arc-blocks. Heat generated in the production of ions within the arc chambers 64, 65, and 66, as explained more fully hereinafter, also assists in preventing condensation of the vapor on the walls of the arc chambers 64, 65, and 66.

Two upstanding strips 75 and 76, formed of tungsten or the like, are secured to the face of the left arc-block 22 cooperating relation with the arc chamber 64. The two strips 75 and 76 comprise a portion of the wall structure of the arc chamber 64 and are arranged in laterally spaced-apart relation to define an upstanding slot there-- between communicating with this are chamber. Also, two upstanding strips '77 and 78, formed of tungsten or the like, are secured to the left arc-block 22, respectively adjacent the strips 75 and 76, and spaced a small distance forwardly with respect thereto. More particularly, the strips 77 and 73 define an upstanding slot therebetween communicating with the arc chamber 64. Thus, the slot defined between the strips 75 and 76 and the slot defined between the strips 77 and 78 constitute an upstanding composite slot 28, formed in the front wall of the left arc'block 22 and communicating with the arc chamber 64.

Similarly, 'two upstanding strips 80 and 81, formed of tungsten or the like, are secured to the face of the central arc-block 23 in cooperating relation with the arc charnber 65. The two strips 3%) and 81 comprise a portion of the wall structure of the arc chamber 65 and are arranged in laterally spaced-apart relation to define an upstanding slot therebetween communicating with this are chamber. Also, two upstanding strips 82 and 83, formed of tungsten or the like, are secured to the central arc-block 23, respectively adjacent the strips 80 and 81, and spaced at small distance forwardly with respect thereto. More particularly, the strips 82 and 83 define an upstanding slot therebetween communicating with the arc chamber 65. Thus, the slot defined between the strips 80 and 8t and the slot defined between the strips 82 and 83 constitute an upstanding composite slot 29, formed in the front wall of the central arc-block 23 and communicating with the arc chamber 65.

And similarly, two upstanding strips 85 and 86, formed of tungsten or the like, are secured to the face of the right arc-block 24 in cooperating relation with the arc chamber 66. The two strips 85 and 86 comprise a portion of the wall structure of the arc chamber 66 and are arranged in laterally spaced-apart relation to define an upstanding slot therebetween communicating with this are chamber. Also, two upstanding strips 87 and 88, formed of tungsten or the like, are secured to the right arc-block 24, respectively adjacent'the strips 85 and 86,

and spaced a small distance forwardly with respect thereto. More particularly, the strips 87 and 88 define 'an upstanding slot therebetween communicating with the arc chamber 66. Thus, the slot defined between the strips 35 and 86 and the slot defined between the strips 37 and 83 constitute an upstanding composite slot 3% formed in the front wall of the right arc-block 24 and communicating with the arc chamber 66;

Three cathode structures 96, 91, and 92 are supported over the respective arc-blocks 22, 23, and 24 and respectively carry three filamentary cathodes 32, 33, 34 in coopcrating relation with respect to the three are chambers 64, 65, and 66. The opposite ends of each of the filamentary cathodes are removably clamped in place by two terminals carried by the associated cathode structure, and the two terminals mentioned are insulatingly supported and are connected to a corresponding source of filament supply. The central portions of the filamentary cathodes 32,33, and 34,'respectively, overhang the top walls of the respective arcbl'ocks '22, 23, and 24; and three mutuaily insulated collimating electrodes 36, 39, and 42 are secured to the top Walls of the respective arc-blocks 22, 23, and 24, each of the collimating electrodes 36, 39, and 42 having a transversely extending slot formed there in and communicating with the corresponding arc chambers 64, 65, and 66, the center transverse slot formed in the collimating electrode 39 and cooperating with the filamentary cathode 33 being illustrated at 40 in Fig. 4. More particularly, the filamentary cathode 32 is spaced a short distance above the collimating electrode 36, the central portion of the filamentary cathode 32 being arranged in alignment with the corresponding transverse slot formed in the collimating electrode 36 and communicating with the arc chamber 64; the filamentary cathode 33 is spaced a short distance above the collimating electrode 39, the central portion of the filamentary cathode 33 being arranged in alignment with the corresponding transverse slot 40 formed in the collimating electrode 39 and communicating with the arc chamber 65; and the filamentary cathode 34 is spaced a short distance above the collimating electrode 42, the central portion of the filamentary cathode 34 being arranged in alignment with the corresponding transverse slot formed in the collimating electrode 42 and communicating with the arc chamber 66.

Three mutually insulated anodes 35, 38, and 41 are secured to the bottom walls of the respective arc-blocks 22, 23, and 24 adjacent the lower ends of the corresponding are chambers 64, 65, and 66 and in alignment with the central portions of the respective filamentary cathodes 32, 33, and 34 and the three transverse slots formed in the respective collimating electrodes 36, 39, and 42.

More particularly, the colimating electrode 36 and the anode 35 are secured to the opposite ends of the arc-block 22 and form end walls of the arc chamber 64; the collimating electrode 39 and the anode 38 are secured to opposite ends of the arc-block 23 and form end walls of the arc chamber 65; and the collimating electrode 42 and the anode 41 are secured to opposite ends of the arcblock 24 and form end walls of the arc chamber 66. The collimating electrodes 36, 39, and 42 and the anodes 35, 38, and 41 are formed of copper or brass and are electrically connected to the respective arc-blocks 22, 23, and 24 to which they are secured.

The negative terminal of one arc supply is connected to the filamentary cathode 32; and the positive terminal of this are supply is connected to the arc-block 22, the collimating electrode 36, and the anode 35. The negative terminal of a second arc supply is connected to the filamentary cathode 33; and the positive terminal of the second arc supply is connected to the arc-block 23, the collimating electrode 39, and the anode 38. Also, the negative terminal of a third are supply is connected to the filamentary cathode 34; and the positive terminal of the third are supply is connected to the arc-block 24, the collimating electrode 42, and the anode 41.

Three upstanding semicircular bathe plates 100, 101, and 102, formed of quartz or the like, are respectively arranged in the arc chambers 64, 65, and 66, each of the bathe plates having a series of longitudinally spacedapart openings formed therein for a purpose more fully explained hereinafter.

Also, the ion transmitter unit 20 comprises associated ion accelerating structure 44 that includes four upstanding laterally spaced-apart metallic strips 103 to 106, inclusive, supported by two laterally extending metallic members 107 and 108, the metallic strips 103 to 106, inclusive, being directly connected to the members 107 and 108 in any suitable manner. The ion accelerating structure 44 is disposed forwardly of the arc-blocks 22, 23, and 24; the two metallic strips 103 and 104 carry two electrodes 109, formed of tungsten or the like, arranged in laterally spaced-apart relation to define an upstanding slit 145 therebetween, arranged in alignment with the slot 28 formed in the front wall of the arcblock 22 and communicating with the arc chamber 64; the two metallic strips 104 and 105 carry two electrodes 110, formed of tungsten or the like, arranged in laterally spaced-apart relation to define an upstanding slit 146 therebetween, arranged in alignment with the slot 29 formed in the front wall of the arc-block 23 and communicating with the arc chamber 65; and the two metallic strips 105 and 106 carry two electrodes 111, formed of tungsten or the like, arranged in laterally spaced-apart relation to define an upstanding slit 147 therebetween, arranged in alignment with the slot 30 formed in the front wall of the arc-block 24 and communicating with the arc chamber 66. All of the metallic strips 103 to 106, inclusive, and the electrodes 109 to 111, inclusive, carried thereby are electrically connected together and to the laterally extending members 107 and 108. The entire transmitter unit 20 is adapted to be supported by the removable end wall of a calutron, in the manner previously noted.

The positive terminals of the three accelerating electrode supplies are respectively connected to the arcblocks 22, 23, and 24, the negative terminals being connected to the ion accelerating structure 44. Also, in

e transmitter unit 20 one of the arc-blocks 22, 23 or 24, and preferably the middle arc-block 23, is electrically connected to the intermediate wall member 61, to the charge receptacle 21 and to the side walls 59 and 60. This arrangement prevents the formation of unduly high electric fields between the left arc-block 22 and the intermediate wall member 61 and the side wall 59 connected thereto; and the formation of unduly high electric fields between the right arc-block 24 and the intermediate wall member 61 and the side wall 60 connected thereto.

Considering now the detailed operation of the ion transmitter unit 20, when the electric circuits for the heaters 71 and 73 are completed the charge receptacle 21 and consequently the charge bottle 52 are heated, whereby the charge 53 is vaporized, filling the cavity in the charge bottle 52. The vapor passes through the tubular member 63 into the vapor distributing chamber 62, whereby this chamber is filled with the vapor. The vapor fills the vapor distributing chamber 62 substantially uniformly and passes through the communicating passages 25, 26, and 27 formed in the walls of the respective arcblocks 22, 23, and 24, into the rear parts of the arc chambers 64, 65, and 66. The vapor then passes through the openings formed in the bafiie plates 100, 101, and 102, into the front parts of the arc chambers 64, 65, and 66, whereby these parts of the arc chambers mentioned are filled with the vapor. More particularly, each of the arc chambers 64, 65, and 66 is thoroughly and substantially uniformly filled with the vapor to be ionized, due to the arrangement of the distributing chamber 62, the communicating passages 67, 68, and 69, and the associated bafile plates 100, 101, and 102.

When the filament supply circuits are completed, the filamentary cathodes 32, 33, and 34 are heated and rendered electron emissive; and when the arc supply circuits are completed between the filamentary cathodes 32, 33, and 34 and the respective arc-blocks 22, 23, and 24, electrons are projected from the central portion of each of the filamentary cathodes toward the respective collimating electrodes 36, 39, and 42. More particularly, some of the electrons from the central portion of each of the filamentary cathodes 32, 33, and 34 pass through the three transverse slots formed in the collimating electrodes 36, 39, and 42, into the associated arc chambers 64, 65, and 66, and proceed toward the corresponding anodes 35, 38, and 41. Accordingly, the collimating electrodes 36, 39, and 42 cause a stream of electrons having a ribbon-like configuration to be projected through each of the arc chambers 64, 65, and 66, whereby the vapor in each of the arc chambers mentioned is ionized.

When the accelerating electrode supply circuit is completed between the arc-block 22 and the ion accelerating structure 44, the positive ions produced in the arc chamber 64 are drawn through the upstanding slot 22 formed in the front wall of the arc-block 22, to form a beam of positive ions having an upstanding substantially ribbonlike configuration proceeding through the slit 1 5 between the electrodes 169; which beam of positive ions is projected through the evacuated tank space iOJ/Ela. the collector block 45 in the calutron, in the manner previously explained. Also, when the second accelerating electrode supply circuit is completed between the arcblock 23 and the ion accelerating structure 44, the positive ions produced in the arc chamber 65 are drawn through the upstanding slot 28 formed in the front wall of the arc-block 23, to form a beam of positive ions having an upstanding substantially ribbon-like configuration proceeding through the slit 146 between the elecrodes 119; which beam of positive ions is projected through the evacuated tank space toward the same collector block 45' in the calutron, in the manner previously explained. And finally, when the third accelerating electrode supply circuit is completed between the arc-block 24 and the ion accelerating structure .4, the positive ions produced in the arc chamber 66 are drawn through the upstanding slot 36 formed in the front wall of the arc-block 24, to form a beam of positive ions having an upstanding substantially ribbon-like configuration proceeding through the slit 147 between the electrodes 111; which beam of positive ions is projected through the evacuated tank space toward the same collector biock 45 in the calutron, in the manner previously explained.

Accordingly, it will be understood that the ion trans- 'mitter unit 2 comprises three mutually insulated ion generators or gas ionizing devices which are supplied with gas from a single charge, and that these gas ionizing devices in conjunction with the associated ion accelerating structure comprise three individual ion transmitters arranged to transmit three corresponding beams of ions within the evacuated tank space in the tank of a calutron. With the present transmitter unit, the three ion beams may be caused to traverse paths of different curvature and may all be brought to a focus on a single receiver, whereby ions of the same isotope but formed in different ion generators may be deposited in the same pocket of the receiver.

While the calutron is illustrated for purposes of r explanation as comprising a transmitter unit including three mutually insulated individual transmitters, the actual number of individual transmitters that maybe used advantageously is limited only by physical considerations. While only the single'calutron 1i embodying a transmitter unit of the general construction and arrangement of the transmitter unit 20 has been illustrated, it will be understood that other calutron geometries and other arrangements of individual transmitters in a single transmitter unit are contemplated.

In view of the foregoing, it is apparent that there has been provided .an improved calutron of the multiple ion beam type, as well as an improved transmitter unit of the multiple ion beam transmitting type.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A calutron comprising a substantially fluid-tight tank, means for evacuating said tank, means for establishing a magnetic field along a given axis through said tank, an ion transmitter unit disposed in said tank and including a plurality of ion generators secured together in side-by-side relation, each of said ion generators being operative to generate ions of a polyisotopic material, means for projecting from said ion generators a corresponding plurality of, ion beams at difierent velocities substantially transversely of said given axis, and a single ion receiver unit disposed in said tank in intercepting relation with said beams and having a plurality of pockets, each of said pockets retaining ions of a particular isotope from each of said beams.

A calutron comprising a substantially fluid-tight tank, means for evacuating said tank, means for establishing a magnetic field along a given axis through said tank, an ion transmitter unit disposed in said tank and including a plurality of mutually insulated ion generaors secured together in side-by-side relation, each of said ion generators being operative to generate ions of a polyisotopic material, a corresponding plurality of electrodes disposed adjacent said ion generators, means including a corresponding plurality of independent sources of potential respectively connected between said ion generators and said electrodes for withdrawing and projecting from said ion generators a corresponding plurality of ion beams substantially transversely of said given axis at diiierent velocities, and a single ion receiver unit disposed in said tank in intercepting relation withsaid beams and having a plurality of pockets, each of said pockets retaining ions of a particular isotope from each of said beams.

3. A calutron comprising a substantially fluid-tight tank, means for evacuating said tank, means for establishing a magnetic field along a given axis through said tank, an ion transmitter unit disposed in said tank and including a plurality of mutually insulated ion generators secured together in side-by-side relation, each of said ion generators being operative to generate ions of a polyisotopic material, a corresponding plurality of electrodes disposed adjacent said ion generators, said electrodes being electrically connected to each other, and means including a corresponding plurality of independent sources of potential respectively connected between said ion generators and said electrodes for withdrawing and projecting from said ion generators a corresponding plurality of ion beams substantially transversely of said given axis, and a single ion receiver unit electrically connected to said electrodes and disposed in said tank in intercepting relation with said beams and having a plurality of collector pockets, each of said pockets being electrically connected to said electrodes for retaining ions of a particular isotope from each of said beams.

4. A calutron comprising a substantially fluid-tight tank, means for evacuating said tank, means for establishing a magnetic field along a given axis through said tank, an ion transmitter unit disposed in said tank and including a plurality of ion generators for producing ion-s of a polyisotopic material, means for Withdrawing and projecting said ions from said ion generators in a corresponding plurality of arcuate and intersecting paths of diiferent radii substantially transversely of said given axis, and a single receiving means disposed in said tank in intercepting relation with said beams for separately retaining ions of a particular isotope from each of said beams.

5. A calutron comprising a substantially fluid-tight tank, means for evacuating said tank, means for establishing a magnetic field along a given axis through said tank, a plurality of ion generators disposed in said tank and arranged in spaced-apart relation, each of said ion generators being operative to generate ions of a polyisotopic material, a plurality of accelerating electrodes respectively associated with said ion generators, a corresponding plurality of sources of different potentials respeotively connected between said ion generators and said accelerating electrodes, whereby a corresponding plurality of ion beams of. different velocities are projected from said ion generators substantially transversely of said given axis and describe arcuate and intersecting paths of difierent radii and the ions of difierent isotopes of the References Cited inthe file of this patent naterial in said ion beams are subjeeted to a segregating UNITED STATES PATENTS mfiuence, and means disposed in said tank for receiving said ion beams substantially at the point of intersection 1348384 Lawrence 1934 thereof and for collecting predetermined portions thereof, 5 4 Sloan July 1935 the collected portions of said ion beams containing a 2'221467 Bleakney 12,1940

given isotope of na'teri al Schutze 2,373,151 Taylor Apr. 10,1945

OTHER REFERENCES 10 Physical Review, vol. XI, No. 4(1918), pages 

1. A CALUTRON COMPRISING A SUBSTANTIALLY FLUID-TIGHT TANK, MEANS FOR EVACUATING SAID TANK, MEANS FOR ESTABLISHING A MAGNETIC FIELD ALONG A GIVEN AXIS THROUGH SAID TANK, AN ION TRANSMITTER UNIT DISPOSED IN SAID TANK AND INCLUDING A PLURALITY OF ION GENERATORS SECURED TOGETHER IN SIDE-BY-SIDE RELATION, EACH OF SAID ION GENERATORS BEING OPERATIVE TO GENERATE IONS OF A POLYISOTOPIC MATERIAL, MEANS FOR PROJECTING FROM SAID ION GENERATORS A CORRESPONDING PLURALITY OF ION BEAMS AT DIFFERENT VELOCITIES SUBSTANTIALLY TRANSVERSELY OF SAID GIVEN AXIS, AND A SINGLE ION RECEIVER UNIT DISPOSED IN SAID TANK IN INTERCEPTING RELATION WITH SAID BEAMS AND HAVING A PLURALITY OF POCKETS, EACH OF SAID POCKETS RETAINING IONS OF A PARTICULAR ISOTOPE FROM EACH OF SAID BEAMS. 